A new type of life-saving heart operation has been successfully performed on a baby in the womb.

The micro-surgical technique allowed the mother to carry her child to full-term, avoiding complications associated with premature births.

It also increased the chance of normal heart development and function in the baby.

This technique could be developed to help other unborn babies in danger of heart failure

Dr Helena Gardiner

The technique, called pulmonary valvuloplasty, has been developed by specialists from Hammersmith and Royal Brompton Hospitals in London.

It is used to unblock the pulmonary valve, which when working normally allows blood to flow from the right ventricle of the heart to the lungs.

However, if the valve fails to develop properly in the unborn child, it can become sticky and prevent normal blood flow through the chambers of the heart.

This prevents growth of one side of the heart and may cause life-threatening complications that put the unborn baby's life at risk.

Even if the child survives to birth it may be plagued by major health problems.

Rare operation

Until now there have only ever been 14 reported world-wide attempts to perforate or stretch foetal cardiac valves - and all but one of these have been on a different valve which leads to the aorta.

Only half of these have been technically successful with just one long-term survivor.

The UK team, led by Dr Helena Gardiner from the Centre for Fetal Care at Queen Charlotte's, operated on an unborn baby with circulation problems 28 weeks into the pregnancy.

They carried out the surgery under local anaesthetic through the mother's abdomen using ultrasound technology for guidance.

The surgeons used a needle to perforate the pulmonary valve and then inflated it using a balloon.

This kept the valve open for five weeks, ensuring a proper flow of blood through the heart.

When the valve closed again, the child had to be delivered, but the extra time in the womb proved to be crucial.

Jamie Maguire, now 18 months old, is healthy and has good blood circulation and a heart that functions normally.

Small target

Lead researcher Dr Helena Gardiner, of the Centre for Fetal Care, said: "For the first time in the UK we have successfully performed balloon dilatation, opening pulmonary valves, on unborn children.

"When these operations are performed, the heart is about the size of a large grape so it's a very delicate and difficult procedure.

"Survival of the babies was our main goal but we were also able to study the reduction in pressure on one side of the heart as we monitored the changing dynamics of blood flow using ultrasound.

"Furthermore, the pregnancy was able to proceed to near full term, preventing the complications which can arise from premature delivery.

"With more experience, better equipment and a growing understanding of the foetus, this technique could be developed to help other unborn babies in danger of heart failure."

One hundred babies are born every week in the UK with some form of heart condition.

Of these, about 3% will be born with problems caused by a faulty pulmonary valve.

Not all of these babies will be able to undergo the procedure.

The research is published in The Lancet medical journal.